I have a client who runs an e-commerce site, and he wants to create a brochure style site for one of his product ranges. The site will contain a lot of good information and images on the product, and is completely legitimate.
However, they want to direct their visitors to the e-commerce pages for the products so they can order them online.
Probably no worse than affiliate links. A problem would be if it's a massive amount of links to the e-commerce site. The safest links would be ones directly to the "buy now" page but then it might also be misunderstood by the purchaser, not quite as legitimate in their eyes if they see they've been directed to another domain.